Piston ring



A July 12,1927.' f, vE. N. BRODERICK PISTON RING Filed Nov, 5, 1920 y m Y munnuml.

l Patented Jixly |12, 1.9274. Y A p .UNITED-'STATES PATENT OFFICE.

ERNEST N. BRODEBICK, OF DETROIT,MIGHIGAN. V

\ PIs'roN anni.

Application med 4November I l This invention relatestopiston ringsand to methods of casting piston rings for interlnal combustion engines and has for yits obl ject the production of a highly elastic ring with awearing surface free from portions.

of such hardness as to cause uneven or excessivewear of the cylinder.

It has been a common practice to manufacture piston rings by making a tubular casting of iron slightly softer than the metal A of which the" cyhnders are cast, and' after boring Aout the interior and turning olf the exterior surface, cutting the tube into nar- ,ture of higher grade rings to cast each ring separately in the endeavor to-secure better castings and more highly resilient rings.

When a small, light casting is made in the 'usual way, there is an outer surface which, because is has chilled so rapidly in` the mold, is very hard; and unless Vthis hard- .cned portion is removed completely, there will be a place in the ring castingharder than the cylinder and this will act to score the cylinder wall. "it the chilled surface is completely removed, the ring is no morev elastic, or but very little more elastic than one' made by cutting sections from a tube as described above. v

I ropose to gain all the advantages of the individually cast ring while obviating itsl disadvantages by] making the shape of the rough castmg such that when the ring is nished the wearing surface will be free' from hard vportions while the remainder of the ring will have alhard and highly elastic surface making it much more resilient than a ring as ordinarily made.. l

To accomplish this result, I make the out-` er periphery of -the casting considerably wider than the inner portion, andthe diameter -of the casting greater than that of the finished ring so that whenl the side fgces are made parallel andthe outer, circumference turned down to-the proper size, all of the hard, chilled exterior portion of the casting will be removed from the wearing surface of the ring'while part' of both side faces and theinner circumference will retain a surface layer of chilled, hard, and elastic metal shading, beyond 5, 1920. smal No. 421,893.

which Willfact as a spring to renden the rin( I A view and a diametral section of the casting; Figs. 3 and Llare respectivelya plan and a diametral section of the finished ring;

Fig. 5 is an enlarged section of the `-pieferred form of casting; 'Y Fig. 6 is a section indicating the contour after the removal of the first portionof the surplus material; Fig. 7 is a section showing the Adistribution of material in the finished ring;

Figs. \8 and 9 are sections of modified structures showing Aother embodiments of the same invention; and

Fig. 10 is a section of other form. of blank.

In the form illustrated in Figs. 5, 6, and 7, representing successive stages of manufacv a fragment of any ture, the casting fory the ring is made with the outer circumference enlarged in width by the addition of laterally; projecting annular portions 10, 10, which extend 'far enough to each side to carry the outer layer of chilled metal indicated at 11,by heavier the plane/of the sides of the finished ring. The casting is also sulficiently greater in diameter than the finished ring so that the removal of the outer circumference in reducing the casting to the diameter of the rin will result the removal of all of the chilled portion from the' wearing surface. After removing 'the excess of metal from the outer circumference and from. the-sides of the outer-edges, only a .small portion of the chilledv metal will be taken from the inner circumference and from the inner portion of the side faces in the finishing grinding as is indicated bythe small space between'the dot-.and-dash line and the section in Fi 7. It willjbe underdimensions shown are greatly f stood thatthe exaggerated The inner portion 12 ofthe casting is free from the' hardened metal formed upon the outer` surfaces of the casting, andfby making the contour-,as shown in Fig. 5, the re lnoval of the projecting portions l0l beyond' .the planes'of the sides of the ring will leaves the soft interior exposed at each' sidefor a short idistance in from the: outer circumference, as indicated at 13, while the cutting off of the 'outer circumference reduce the 'a plan l,

4o' circumference to a point lbeneath the hardblank tol the diameter of the ring will leave a soft wearing surface 14. Thus as the ring wears, it may be reduced to a diameter such as to necessitate its replacement before the `hard portions 11 left on the sides Will be The dot-and-dash outlines in Figs. 8 and 9 indicate other sections that -may be used to give different distributions of the hard- A vened portions left in the finished ring. u With the straight sides shown in Fig/'8,v it

willbe noted that there will be less of the chilled metal left than when the sides are curved as in Fig. 9. Other similar cross sections may obviously beemployed, the essen- .tial features in each case being the excess of metal at each side, and the greater diameter Y of the casting as compared with the finished ring to insure that all of the metal of undesirable hardness may be removed from the outer periphery and inward from the edges while leaving the U-shaped, chilled, spring portion extending outward from thel lnner circumference.

In the form of blank indicated in Fig.

10, a cylinder 15 is cast with a series of internal channels 16, the internal surface of the cylinder and the lchannels vbeing chilled in casting. The cylinder iscut into sections the cuts being in the-plane of the bottom o the-channels, and the ring blanks .are then finished as in the cases where the blanks are separately cast, by the removal of the outer ened portion, and by the removal of a relatively small amount from the sides and inner circumference as indicated at 17` in The hard surface layer 1s 1ndashed lines. dicated -by the numeral 11 in this figure and by the vdarker section lining. y

It has previously been proposed to form ,y piston rings having upon the periphei a v eracing of anti-friction material of a di ent composition-from that constituting the body of the ring, but rings made by the process disclosed herein have all portions of the ring produced concurrently to provide a permanent 'molecular arrangement of the ring with one of the zones having less hardness than that of the cylinder with which it is to be used, and another zone integral therewith and. composed of the same materials, but having the quality of greater resihency because of a difference in molecular arrangement due -to the more rapid cooling of this portionI because of its direct contact with the .walls of the mold.

' Substantially all comercial metallic castings consist of a mixture of various ingredients capable of varying molecular arrangements, andthe quality of the finished prod.- uct is dependent upon the manner in which these various arrangements occur during the process of manufacture. The resilient outer skin which formsthe U-shape hardened portion left as the surface of the inner circumference and the inner portion of the sides is composed of substantially the same chemical ingredients as is the material forming the softer outer periphery, the difference in hardness being due principally tothe variation in the molecular arrangement of the constituent material, while the molten alloy is hardening'in the mold.

lfVhat I claim is 1. An integral piston ring having its outer circumference and a portion of each side face extending inward from the circumference formed of a metal of less hardness than that-of the cylinder with which it is to be used and having the surface of the inner circumference and theremaining portion Iof each side face composed of the same metal having its constituent elements provided with a molecular arrangement -of greater hardness than that of the outer circumference.

2. An integral piston ring comprising two portions composed of the same elements, one lrelatively soft and the other relatively hard, the soft portion forming the surface of the outer circumference. and extending inward from the outer edges, and the hard portion arranged as the U-shaped exterior of .the inner circumference and the adjacent surfaces of the side faces.

3. A piston ring having the inner circumference and the inner portion of each side face formed` of chilled cast iron, and the outer circumference and tlie'outer portion of each side face formed of cast iron devoid of chilled portions.

4. The method of producing piston rings 110 which includes casting an annular blank having a greater diameter than the finished ring and an outer edge thicker than the inner edge, the entire surface havinga hard, chilled portion, then removing the chilled 115 loc portion from the outer circumference and reducing the diameter to that desired for the finished ring, and removing the chilled portion fro'mboth sides of the outer edge.

5. The method of producing piston rings 12@ which includes ycasting an annular.. blank having ahard'ychilled surface layer and re'- moving the-entire hard layer from the outer circumference and from the portion of the sides adjacent thereto while retaining the 125 major part of the hard layer on the remaining portion of the sides and on the inner circumference. 6. The method of producing a piston ring which comprises casting a blank of greater dimensions than desired lfor the rin and reducing ,the blank to.the desired imention ef the finished ring, so that little is removed, the hardened portion being left substanti ally-as cast, and theouter circumference of the blank and the portion ofthe side faces adjacent thereto having a conguration such that enough material must be removed in reducing that portion tothe dimensions of the finished ring to ensuretmhe removal of any hardened portions Athat may be lformed near the surface.

7 The method of producing a piston ring which comprises casting a -blank'which has a y part, having approximately vthe .dimensions desired. for the inner circumference and the portions of the side vfaces adjacent thereto.

4in the finished ring,1 castfwith a; chill,A the portion of the blank from which the outer yfwhich surface y,is removed in finishin circumference and the side faces adjacent 28 l f thereto are ormedhaving dimensions suciently greater than those of the finished ring to ensure the removal of the. surface hardening produced when the blankI is cast. 8. A piston rin having portionsldiferin as to .resiliency c aracteristics, one of sai portions being of less hardness than thatJ of the cylinder with .which it is to be used, said portion forming the Wearing face and a portion of each side face' ofthe ring, another of said portions being of greater resiliency than that forming the wearing surface,'said port-ions'being concurrently cast.

' 9, A piston ring blank comprisinga body of greater width in cross-section at its outerA cast lwith a chilled rsurface, a portion pif t e Iblank to bring it to proper cross-sectlonal configuration.4 s A In testimony whereof aix my signature.

ERNEST N. BRoDERIcK. j

,fao

40 :than at its inner periphery, said blank being' 

